OBESE Scots spend 50% more time in hospital than patients with a healthy weight, according to new research that lays bare the financial drain of the nation's burgeoning waistline.

Statistics spanning more than two decades and comparing people of varying body mass indices (BMI) found that obese people spent an average of 26 days in hospital compared to 17 for someone in the healthy weight range. The difference is equivalent to obese people spending 53% more time in hospital than their slimmer peers.

The study, led by researchers at Edinburgh University and published today in the Scottish Medical Journal, is one of the first to examine the link between BMI and time spent in hospital and comes amid increasing fears about the cost of obesity to the health service.

Obesity costs NHS Scotland around £175 million a year and there are already fears that by 2020 the cost could swallow around one-quarter of the total NHS budget. Only last week experts writing in The Lancet predicted there could be 26 million obese people in Britain by 2030.

Dr Sarah Wild, a reader in epidemiology and public health at Edinburgh University, said they had found an “independent” association between obesity and the number of days spent in hospital, even after taking into account other factors such as socio-economic status.

She said: “What we weren’t able to look at was whether people were going into hospital with the same conditions but ending up staying longer because of complications related to being overweight, or whether they were having more admissions because they had more health conditions.

“It’s probably a combination of the two, but even with a simple operation you’re more likely to have complications if you’re overweight. You’re more likely to get an infection and need to stay in hospital and then have antibiotics, which of course ups the cost.”

The study included almost 7000 men and 8700 women aged 16-74 from throughout Scotland. They were split into four BMI groups – underweight, healthy, overweight and obese – and the researchers then added up how many days each participant spent in hospital between 1981 and 2004.

The researchers found that an obese person spent an average of 26 days compared to a healthy person’s 17, while an overweight person had spent an average of 20 days in hospital. Underweight participants averaged 25 days, but the researchers believe this is skewed by weight loss brought on by certain illnesses, such as cancer.

The researchers wrote: “The treatment of the complications of overweight and obesity during hospital admissions forms an important component of the costs of overweight and obesity and there are, therefore, economic as well as human arguments for maintenance of a healthy weight.”

Tam Fry, chairman of the National Obesity Forum, said the figures did not surprise him.

He said: “It has been well-known that the cost of obesity to the NHS, whether it be in the community or in hospital, is excessive already. There’s a lot of literature which shows that unless something is done about it now it could even break the NHS. This piece of research just confirms how much of a problem it is and how much it costs.”

However, he added that health boards were pursuing a “false economy” by increasingly refusing obese patients expensive gastric band surgery in an attempt to cut costs.

He said: “It’s a large expenditure at the beginning, with the operation, but if everything goes well then the cost-saving will be substantial for the NHS.”

The Scottish Government launched an action plan in March focused on preventing people become obese in the first place.

A spokeswoman for the Scottish Government said: “We cannot expect people to be able to change their behaviour alone as the environment we live in today means that for most people weight gain becomes almost inevitable. We have to make serious changes that will transform our entire living environment and make healthy choices easier.

“Our obesity strategy aims to work across all areas of Government to ensure that policies are directed at supporting people to achieve and then maintain a healthy weight.”